Soil carbohydrates, including microbial extracellular polysacchrides, stabilize soil aggregates and improve soil structure. This study examined whether short‐term managment of C inputs by cover crops and tillage affected polysaccharide‐mediated macroaggregation. Soil was sampled from a Californa prune (Prunus domestica L.) orchard where an experiment comparing four management techniques, permanent grass cover crop, mowed cover crop, no‐till herbicide, and conventional tillage, had been in place for two seasons. Cover crops significantly increased saturated hydraulic conductivity, acid‐ex‐tractable heavy‐ fraction carbohydrates (those in soil denser than 1.7 g/mL), and macroaggregate slaking resistance over clean‐cultivated or herbicide treatments. Heavy‐fraction carbohydrates are probably mainly composed of microbial extracellualr polysaccharides produced in response to cover‐crop C inputs. Heavy‐fraction carbohydrates were significantly correlated with aggregate stability and satureated hydraulic conductivity, while total organic C and lightfraction carbohydrates were not. There were no differences between soil under herbicide and clean‐cultivation treatments, showing that tillage alone did not measurably affect carbohydrate or soil structure. Heavy‐fraction carbohydrates were shown to be important in the initial improvement of soil structure by cover crops.

No abstract

No abstract

No abstract

Active wind‐borne sand dunes, which lead to covering of fertile soils and agricultural fields, are one of the main problems in desertified lands worldwide, and stabilizing them poses a significant challenge. Such sand dunes may be naturally stabilized by biocrusts (biological soil crusts). One of the main restraints of biocrust development is the typical lack of fine particles in sand dunes. A possible artificial source of fine particles is coal fly‐ash, which is the by‐product of power stations and comprises of particles having a diameter of less than 100 µm. This study tested the influence of the coupling effects of coal fly‐ash and bio‐inoculant of filamentous cyanobacteria, isolated from natural stabilized sand dunes nearby, on the soil surface of active sands for increasing resistance to wind erosion. Boundary‐layer wind tunnel experiments were conducted in experimental plots within a greenhouse for examining the effects of adding coal fly‐ash and bio‐inoculant to active sands. The biocrust development was evaluated via several physical and bio‐physiological variables. In all the physical measurements and the bio‐physiological variables, the treatment of “sand + inoculum + coal fly‐ash” showed significant differences from the “sand‐control”. The combination led to the best results of surface stabilization in boundary‐layer wind tunnel experiments, with the lowest sand fluxes. The filamentous cyanobacteria use the fine particles of the coal fly‐ash as bridges for growing toward and adhering to the large sand particles. The cumulative effects of biocrusts and coal fly‐ash enhance soil surface stabilization and may allow long‐term sustainability. Copyright © 2016 John Wiley & Sons, Ltd.